Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) are dangerous human pathogens. Traditionally, MRSA infections occurred exclusively in hospitals and were limited to immunocompromised patients or individuals with predisposing risk factors. However, MRSA strains have recently emerged that can cause severe infections (such as necrotizing fasciitis) or death in otherwise healthy adults. These strains are increasingly community-acquired, and can be contracted outside of the health care settings. As is true for hospital-acquired MRSA, the incidence of these community-associated (CA)-MRSA infections is increasing. For example, the majority of infections in patients reporting to emergency departments in the United States are now due to CA-MRSA. Individuals with indwelling medical devices are particularly at risk for infection with S. epidermidis, including MRSE.
It is unclear what makes CA-MRSA strains more successful at causing human disease compared with their hospital-associated counterparts. Given the foregoing, it would be desirable to know the cause of the increased virulence of CA-MRSA, and to have methods of treating, ameliorating, and preventing MRSA. Similarly, it would be desirable to identify virulence factors of methicillin-resistant staphylococcus and to have methods of treating, ameliorating, and preventing these infections.